The present invention relates to a method and apparatus for decoding a lock of the wafer combination type such as that commonly marketed under the trademark SCHLAGE.
Such wafer combination lock is found primarily in apartment complexes because it is a master-keyed type of lock, that is, there is a master key which will open all of the locks in a particular complex. In such locks a plurality of wafers, which are essentially semi-circular discs having a radial protrusion or pin, are inserted into slots arranged from front to rear in columns of two in a keyway cylinder. The wafers are spring biased, and depending on the type of wafer, the pin either extends outwardly of the keyway cylinder or retracts under normal bias action of the springs. The purpose of the pins is to prevent the keyway cylinder from turning and thus opening the lock. Only when the proper key is inserted will all of the pins retract and allow the lock to open.
There are three types of wafers used in such locks: "series;" "combination;" and "master" wafers. For each wafer there are two possible orientations. "Series" wafers are either "S1" or "S2," and combination wafers are "odd" or "even." The single master wafer (if used) has an orientation opposite that of the series wafers. All series wafers have the same orientation.
All three types of wafers, "master," "series" and "combination," resemble generally the letter "C." Each is a semi-circular disc with two extending arms, and an outwardly radially-extending pin or protrusion, and a second protrusion or tooth on one arm of the wafer which acts as a seating member for springs which bias the wafers in a predetermined fashion. Both protrusions lie in the plane of the wafer.
The keyway cylinder comprises a frame portion in which is located the master wafer column and seven other wafer columns for the series and combination wafers. The series and combination wafers may be arranged according to the desire of the user; however, there will always be 4 combination wafers and at least one series wafer. If desired, there may be one or more columns left completely blank with no wafer at all.
The orientation of these types of wafers in the columns of the keyway cylinder determines the alpha-numeric code of the lock and provides all of the information necessary to cut a key that will open the lock.
Heretofore, it has not been possible to manufacture replacement keys for wafer combination locks without entirely removing the lock from its fixed surroundings, i.e., the door. This is because in order to make a replacement key, it is necessary to actually see the wafers that are used in the combination lock and visually observe the type and orientation of each wafer used in the combination. Only in this way could an alpha-numeric code, representing the orientation and position of cuts to be made on a key blank, be obtained.
Thus, if it were possible to determine for each wafer column the type of each wafer, that is, whether "combination" or "series," and its orientation, without disassembling the lock, it would be possible to determine the code for the lock and make a key corresponding to the code which would fit and open the lock.